There are two atrioventricular (AV) valves in the heart; one on the left side of the heart and one on the right side of the heart. The left side AV valve is the mitral valve and the right side AV valve is the tricuspid valve. Both of these valves are subject to damage and dysfunction requiring the valves to be repaired or replaced.
The mitral and tricuspid valves differ significantly in anatomy. While the annulus of the mitral valve is generally D-shaped, the annulus of the tricuspid valve is more circular. The effects of valvular dysfunction vary between the mitral and tricuspid valves. For example, mitral valve regurgitation has more severe physiological consequences to the patient than does tricuspid valve regurgitation, a small amount of which is tolerable.
In mitral valve insufficiency, the valve leaflets do not fully close and a certain amount of blood leaks back into the left atrium when the left ventricle contracts. As a result, the heart has to work harder by pumping not only the regular volume of blood, but also the extra volume of blood that is regurgitated back into the left atrium. The added workload creates an undue strain on the left ventricle, and this strain can eventually wear out the heart and result in morbidity. Consequently, proper function of the mitral valve is critical to the pumping efficiency of the heart.
Mitral and tricuspid valve disease is traditionally treated by either surgical repair with an annuloplasty ring or surgical replacement with a valve prosthesis. Surgical valve replacement or repair, however, is often an exacting operation. The operation requires the use of a heart-lung machine for external circulation of the blood as the heart is stopped and then opened during the surgical intervention. Once the heart is opened, the artificial cardiac valves and/or annuloplasty rings are sewed in under direct vision.
Surgical repair and/or replacement of the AV valves can expose patients, especially elderly patients, to many risks. A percutaneous repair or replacement procedure that could be performed under local anesthesia in the cardiac catheterization lab, rather than in cardiac surgery, could therefore offer tremendous benefits to these patients. Consequently, an apparatus for replacing a diseased AV valve using a minimally invasive, percutaneous approach would be very helpful in providing additional opportunities to treat patients with valvular insufficiency and/or end stage heart failure.